Geospatial Information Change Detection And Update Based On Volunteered Geospatial Information

As the development of the Internet technology, citizens are increasingly involved in the Internet information sharing process. Now, the user-generated content is becoming an important source of the Internet information. The widely applications of mobile devices and the popularization of GIS knowledge in citizens are making good foundation to the sharable GIS in UGC. Then VGI (Volunteered Geography Information) emerged under this environment, the spirit of VGI is that users interoperate on the Internet and offers data voluntarily, which means everyone is authorized to operate the GIS data and they can update VGI in the open geospatial data bases dynamically as well.In recent years, a lot of volunteered GIS web sites and applications based on user-generated have been developed, like Wikimapia, Google Map maker, and OpenStreetMap, etc. These websites and applications have been extracted many users because of the good user-experience and abundant data. Addtionally, the features of volunteered data represent on-time data updating, rich sentimental information, and detail descriptions, therefore the data can be applied in the research and industries.The advantage of VGI is to update the data fast and can be used as data source of guiding professional GIS data updating VGI data comes from the public contributes, the lack of professional equipments and knowledge could probably bring about data quality issues during VGI data gathering and production. Traditionally, professional survey combined outdoor surveying and remote sensing to update the data, the standards of updating are more strict, but the timeliness and updating cycle are limited and are short of abundantly sematic detailed information. This paper mainly emphases how to make the VGI as an effective data source of professional survey department to detect the changed for updating. From all of the above, this study will start out at the quick detecting the change, extracting and updating the spatial data, studying the issues of VGI change information in the discovering, extraction, validation, and multi-database correlation in updating process, to explore the method and key techniques of spatial data change detection and updating based on the VGI data. Our research can be summarized as below:Deeply analyzed the development history and operation mechanism of mainstream VGI project platform and the data updating model of current professional surveying department both in domestic and aboard, this paper summarized the data types and characteristics of VGI data, discussed the issues like the data availability of applying VGI data as data updating source in professional survey department, proposed the spatial data change detection and updating framework based on VGI.Analyzed the current homonym element matching method of vector data, this paper proposed the multi-level spreading and increment recognition algorithm based on the characters of city road network in the vector data of VGI. We extracted the highest level semantic features from the matched data to obtain the initial spreading unit, this unit would be matched with the corresponding feature in the referenced data, the unit will spread to the whole road network by matching all the the semantic, geometry, and spatial topology information in the road arcs and nodes until all the road arcs are marked.Analyzed the various knowledge that existed in the vector data of city road network and the high-resolution images, this paper applied the changed data from VGI as priori knowledge, quickly captured the changed area of image, validated the reliability of the changed data by comparing the meta data and feature information of the VGI data and the latest high resolution remote sensing images.According to the actual demands of GIS data production department, this paper proposed data updating rules in multi-databases, which can be achieved a linked data updating in multi-databases under a distributed environment. We designed and implemented the prototype, achieved more efficient incremental data updating with an overall process of storing, objecting and publishing of changed data.Based on the method above, we can solve the existing problems in the VGI as data updating source for professional survey department. VGI is based on the public user’s knowledge about geographic information, which is different from the professional data collected by traditional survey and mapping method, also have high currency and rich details. This kind of data is very valuable in the industries like transportation, emergency response which have high requirements about the timeliness and details of data. In the future research, we will pay more attention to the data quality, analyze the validation of VGI data in the public audit method, and achieve the overall process from detection to validation of data quality, then build a more efficient geospatial data updating system.